A sealing device of this kind has become known through DE-AS 23 25 000.
The known sealing device is characterised by an extremely small leak rate and a very long lifetime. Occasionally, however, elevated leak rates have been observed.
The underlying purpose of the invention is therefore to improve the sealing effect of the known sealing device and to increase its lifetime.
This purpose is achieved in accordance with the invention in that, in the pressure-less state, the sealing ring, as viewed in the radial direction with respect to the axis of the second machine component, is at least partially separated from a low pressure side of the groove, in that the sealing ring is pivotable towards the low pressure side under the application of pressure and/or through the frictional force between the sealing ring and the peripheral surface, and in that the sealing ring forms a sealing edge with respect to the peripheral surface.
The sealing device in accordance with the invention thereby has the essential advantage that it can be mounted without a prominent sealing edge. The cross-sectional shapes of this type of sealing ring can be simple since pressure loaded and unloaded surfaces can adjust themselves relative to the sealing edge in accordance with the degree of pivot of the sealing ring from the pressure-less into the pressure-loaded state.
If the sealing device is utilized in the pressure-less state and for machine components which move back and forth with respect to each other, the sealing ring pivots from an installed position into a working position in such a fashion that it always tilts on the groove edge, formed on the stationary machine component, which is opposite to the direction of motion of the moving machine component. The low pressure side N corresponds in this case to the side to which the sealing ring is pivoted.
The sealing ring in accordance with the invention is biased by means of a biasing element and its surfaces directed towards the groove sides form an acute angle therewith which in a pressure-less state lies between 10.degree. and 40.degree..
If the sealing ring is symmetrically constructed, it is also easy to mount since attention must not be paid to the direction of installation. The sealing ring, in the case of symmetric configurations, can be subjected, in a direction independent fashion, to a hydraulic pressure in such a fashion that the pivoting process in accordance with the invention establishes itself.
The particularly advantageous application of the sealing configuration according to the invention as a shaft and piston seal has been confirmed by long-running experiments. The durability is substantially increased compared to known sealing devices for reduced leak rates.
If the sealing ring is manufactured from polytetrafluoroethylene, a sealing ring which is symmetric in the pressure-less state can be formed into an asymmetric sealing ring in the pressure-loaded state. Thereby the sealing ring material flows into free spaces given by diagonal surfaces, the free spaces establishing themselves due to the pivoting of the machine component in the groove.
Sealing rings made from polyurethane are particularly suitable for piston seals because they can be subjected to alternating pressure from different directions and also exhibit a very stable shape when pressure-loaded. The sealing device in accordance with the invention is also applicable as a rotational seal. Towards this end a rotational movement with the moving mechanical parts is compensated for by a large area seating of the sealing ring on the low pressure side of the groove.
The sealing configuration according to the invention is also applicable as a shaft seal in a pressure-less state. The pivoting motion into the working position takes place via friction between the sealing edge and the surrounding area which is to be sealed.
Clearly, the groove sides lying across from the oppositely positioned front surfaces of the sealing ring can be tilted in the pressure-less state. The front sides of the inventive sealing ring which face the sides of the grooves can also exhibit differing tilts or could be continuously deformed. If the groove sides of the first machine part are tilted with respect to a plane through the symmetry axis of the second machine part the sealing ring in accordance with the invention can exhibit a particularly simple cross-sectional shape. In a preferred configuration, the sealing ring in accordance with the invention is symmetric to a plane which is perpendicular to the plane through the symmetry axis of the second machine part. This simplifies the production of a sealing ring of this type and the sealing ring according to the invention can be simply and easily utilized for applications with which a change in pressure takes place from one groove side to the other.
In further configurations of the invention the first and second sealing ring areas are tilted relative to the symmetry axis and configured in a parallel fashion and the groove sides of the first machine part are at right angles to the symmetry axis. This has the advantage that the sealing ring, due to the wedge angle between the peripheral area and the seating area exhibits a prominent pressing maximum in the vicinity of the sealing edge and allows for a reverse transport of the fluid present at the actual low pressure side N.
Further advantages can be derived from the description of the accompanying drawing. Likewise the characterising features which were mentioned above and those which will be further described below in accordance with the invention can be utilized individually or in arbitrary mutual combination. The suggested embodiments are not to be interpreted as sole enumerations, rather have exemplary character.